DirectX 12 is an expert API which builds on knowing the ins & outs of DirectX 11. DirectX 12 is an extremely low-level API designed for graphic experts who have a solid understanding of the architecture of modern GPU hardware, and can essentially write the DirectX 11 Runtime from scratch. Both DirectX 11 and DirectX 12 provide access to the same hardware features on Windows 10, but drive the hardware in different ways which can allow a well-optimized DirectX 12 engine to achieve much lower CPU overhead than in DirectX 11.